Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. An electronic device comprising: a card interface having one or more card interface terminals and configured to read data from a payment card during a read of the payment card at the electronic device and to generate a data signal that represents the data read from the payment card; a signal generator configured to generate an interference signal and to introduce the interference signal to the data signal within the card interface as an electrical current received via one of the one or more card interface terminals; and a filter configured to: receive, as an electrical current at a first input terminal via one of one or more card interface terminals, a composite signal including the interference signal and the data signal that represents the data read from the payment card, generate an output signal that represents the data read from the payment card by filtering the interference signal from the composite signal, and output, at an output terminal, the output signal.
An electronic device (like a payment terminal) protects card data by adding an interference signal. It reads card data via a card interface, generating a "data signal." A signal generator creates an "interference signal" that is mixed with the data signal *inside* the card interface. This combined signal ("composite signal") then goes through a filter. The filter removes the interference, leaving a clean data signal that's then output. The key is that the interference is added *before* the signal leaves the card interface, making it harder for attackers to intercept the raw data.
2. The electronic device of claim 1 , wherein the filter is further configured to: receive, at a second input terminal, the interference signal.
The electronic device described previously improves filtering by feeding the interference signal directly into the filter. The filter now has two inputs: the composite signal (data + interference) and the pure interference signal. This helps the filter more accurately remove the interference, resulting in a cleaner data signal. The filter uses both the combined signal and the independent interference signal for better noise cancellation.
3. The electronic device of claim 2 , wherein said generating of the output signal includes generating the output signal by filtering the interference signal from the composite signal using common mode rejection so that the interference signal does not appear in the output signal.
The electronic device described in the previous two claims uses common mode rejection in its filter to remove the interference signal. The filter receives the composite signal (data + interference) and the interference signal itself. Common mode rejection cancels out signals that are present on both inputs, effectively eliminating the interference signal from the output. The resulting output signal contains only the card data, free from the added noise.
4. The electronic device of claim 1 , wherein the filter is further configured to: receive, at a second input terminal, at least a portion of the output signal to form a negative feedback loop.
The electronic device described previously uses a negative feedback loop in its filter design. A portion of the filter's *output* signal is fed back into the filter's *input*. This feedback loop helps to stabilize the filter and improve its accuracy in removing the interference signal. The output signal is sampled and used to adjust the filtering process in real-time.
5. The electronic device of claim 4 , wherein the first input terminal is a non-inverting input terminal, and wherein the second input terminal is an inverting input terminal.
In the negative feedback filter design described previously, the filter's first input terminal (receiving the composite signal) is a non-inverting input, and the second input terminal (receiving the feedback signal) is an inverting input. This specific configuration of inverting and non-inverting inputs is a common way to implement negative feedback in operational amplifiers, ensuring proper signal processing and stability in the filter circuit.
6. The electronic device of claim 1 , further comprising: a processor coupled to the signal generator and configured to trigger generation of the interference signal, adjust a parameter value of the interference signal, and filter the interference signal from the data signal by decoding the output signal in a particular manner based on the parameter value.
This electronic device controls the interference signal and filtering process using a processor. The processor triggers the signal generator to create the interference. It can also change characteristics ("parameter values") of the interference signal, such as timing or strength. The processor also plays a role in filtering by decoding the filter's output signal. The way it decodes depends on the parameters of the interference signal used; the decoding manner corresponds to the specific interference signal generated.
7. The electronic device of claim 6 , wherein the parameter value comprises any of a timing value, a randomness value, a frequency value, a spectrum value, a magnitude value, or some combination thereof.
The "parameter value" of the interference signal, as described in the previous claim, can be any of the following: its timing (when it occurs), its randomness (how unpredictable it is), its frequency (how rapidly it changes), its spectrum (the range of frequencies it contains), its magnitude (its strength), or any combination of these. Changing these parameters makes it harder for an attacker to predict and remove the interference.
8. The electronic device of claim 1 , further comprising: a configuration circuit coupled to the signal generator and configured to adjust the interference signal based on attributes of the filter.
The electronic device contains a configuration circuit to adjust the interference signal based on how the filter is designed ("attributes of the filter"). This ensures the interference signal is optimally tailored to be removed by that particular filter, making the data protection more effective. The configuration circuit adapts the interference signal to maximize the filter's ability to remove it while leaving the real data intact.
9. The electronic device of claim 8 , wherein the configuration circuit includes high pass filter components and resistor divider components that allow the configuration circuit to convert the interference signal from a digital signal to an analog signal.
The configuration circuit described in the previous claim uses high-pass filter components and resistor divider components. These components are used to convert the interference signal from a digital signal (easy for a processor to control) into an analog signal (suitable for mixing with the analog card data). This allows the processor to control the interference using digital logic, while still working with the analog signals from the card reader.
10. The electronic device of claim 1 , further comprising: an amplitude control unit coupled to the signal generator and configured to adjust a magnitude of the interference signal based on an amplitude of the data signal generated during the read of the payment card.
This electronic device adjusts the strength ("magnitude") of the interference signal based on the strength ("amplitude") of the data signal coming from the card reader. This makes the interference more effective because it adapts to the signal it's trying to protect. An attacker can't simply filter out a constant interference signal, because its characteristics are tied to the card data itself.
11. The electronic device of claim 10 , wherein the amplitude control unit is an automatic gain control unit configured to adjust a gain of the interference signal so that the magnitude of the interference signal corresponds to the amplitude of the data signal generated during the read of the payment card.
The amplitude control unit from the previous claim is an automatic gain control (AGC) unit. The AGC adjusts the "gain" (amplification) of the interference signal so that its magnitude closely matches the amplitude of the card data signal. This makes the interference blend in better with the card data, making it harder for attackers to differentiate between the two.
12. The electronic device of claim 1 , wherein the interference signal is a pseudo-random noise signal.
The interference signal is a pseudo-random noise signal. This means it looks like random noise, but it's actually generated by a deterministic algorithm. This makes it hard for an attacker to predict and remove, but the device itself can recreate the exact same "random" signal to remove it during filtering.
13. The electronic device of claim 1 , wherein the signal generator is an integrated circuit.
The signal generator, which creates the interference signal, is an integrated circuit (IC). This means it's a small, self-contained electronic component that performs the signal generation function. This helps to miniaturize the device and makes it easier to manufacture.
14. The electronic device of claim 1 , wherein the one or more card interface terminals comprise a plurality of card interface terminals, wherein the interference signal is provided to a first card interface terminal of the plurality of card interface terminals, and wherein the composite signal is received via a second card interface terminal of the plurality of card interface terminals.
The card interface has multiple terminals. The interference signal is injected into the data signal via one terminal, and the resulting composite signal (data + interference) is received via a *different* terminal. Separating the injection and reception points further complicates any attempt to extract the original data signal before it reaches the device's internal filtering.
15. A method comprising: generating a data signal at a card interface of a first device; generating an interference signal by a signal generator; providing the interference signal as an electrical current to one of one or more card interface terminals of the card interface; combining the interference signal with the data signal within the card interface to form a composite signal; receiving the composite signal as an electrical current at an input terminal via one of the one or more card interface terminals; filtering the interference signal from the composite signal between the input terminal and the output terminal of the first device to form a filtered data signal; and transmitting the filtered data signal via the output terminal to a second device coupled to the first device.
A method for protecting card data involves generating a data signal from a card reader, generating an interference signal, injecting the interference signal into one of the card interface terminals, creating a composite signal (data + interference), receiving this composite signal through another card interface terminal, filtering out the interference to get a clean data signal, and then transmitting this cleaned signal to another device. This process protects data from being intercepted while in transit between the card and the device.
16. The method of claim 15 , wherein said transmitting of the filtered data signal occurs over a wired connection.
The method of transmitting the filtered data signal, as described in the previous claim, happens over a wired connection. This distinguishes it from wireless transmission methods and is relevant in the context of card readers that directly connect to point-of-sale systems or other devices via cables.
17. The method of claim 15 , wherein the interference signal is a Gaussian noise signal.
The interference signal used in the method described previously is a Gaussian noise signal. Gaussian noise is a specific type of random noise with a characteristic distribution. This choice of noise type can impact the effectiveness of the data protection and the design of the filter.
18. The method of claim 15 , wherein the one or more card interface terminals comprise a plurality of card interface terminals, wherein the interference signal is provided to a first card interface terminal of the plurality of card interface terminals, and wherein the composite signal is received from a second card interface terminal of the plurality of card interface terminals.
In the method described previously, the card interface has multiple terminals. The interference signal is sent through *one* terminal, and the composite signal (data + interference) is received through a *different* terminal. This physical separation adds a layer of security, making it harder for attackers to intercept the original data signal.
19. A payment card reader comprising: a card interface having one or more card interface terminals and configured to read a first data signal from a payment card during a read of the payment card at the payment card reader; a first signal generator configured to generate a first interference signal and to provide the first interference signal as an electrical current to one of the one or more card interface terminals; and a first amplifier having a first input terminal, a second input terminal, and a first output terminal, wherein the first amplifier is configured to: receive, at the first input terminal, a first composite signal as an electrical current via one of the one or more card interface terminals, the first composite signal comprising the first interference signal and the first data signal, generate a first output signal by filtering the first interference signal from the first composite signal, and output, at the first output terminal, the first output signal.
A payment card reader protects card data by adding interference. The card reader has a card interface which reads card data generating a "data signal". A signal generator creates an "interference signal", injected into one of the card interface terminals. An amplifier then receives the mixed signal ("composite signal") through a card interface terminal, filters out the interference, and outputs a clean data signal. This protects the card data from being intercepted by unauthorized devices.
20. The payment card reader of claim 19 , wherein the card interface is further configured to read a second data signal from the payment card during the read of the payment card at the payment card reader, the payment card reader further comprising: a second signal generator configured to generate a second interference signal; and a second amplifier having a third input terminal, a fourth input terminal, and a second output terminal, wherein the second amplifier is configured to: receive, at the third input terminal, a second composite signal comprising the second interference signal and the second data signal, generate a second output signal by filtering the second interference signal from the second composite signal, and output, at the second output terminal, the second output signal.
The payment card reader described in the previous claim extends the protection to *multiple* data tracks on the card. It reads a second data signal. It also generates a second interference signal and uses a second amplifier to filter the second composite signal (second data signal plus second interference). The second amplifier outputs a second clean data signal. Essentially, it duplicates the protection mechanism for a second data stream.
21. The card reader of claim 20 , wherein the first signal generator and the second signal generator are such that the first interference signal and the second interference signal include non-identical pseudo-random noise patterns.
The card reader, as described in the previous two claims, uses *different* pseudo-random noise patterns for the first and second interference signals. This means the two interference signals are not identical and appear completely uncorrelated, even though they might share some statistical properties. The signals utilize non-identical pseudo-random noise patterns. This makes it significantly harder for an attacker to filter out both interference signals simultaneously.
22. The card reader of claim 19 , wherein the first amplifier is further configured to: receive, at the second input terminal, the first interference signal, wherein said generating of the first output signal is carried out by applying common mode rejection in relation to the first and second input terminals of the first amplifier.
The amplifier within the card reader, as described previously, filters the interference signal using common mode rejection. The amplifier receives the composite signal (data + interference) at one input terminal and the pure interference signal at another input terminal. Common mode rejection cancels out signals present on both inputs, thus eliminating the interference. The common mode rejection specifically applies to the first and second input terminals of the first amplifier.
23. The payment card reader of claim 19 , wherein the one or more card interface terminals comprise a plurality of card interface terminals, wherein the interference signal is provided to a first card interface terminal of the plurality of card interface terminals, and wherein the composite signal is received from a second card interface terminal of the plurality of card interface terminals.
The card reader’s card interface has multiple terminals. The interference signal is injected into the data signal via *one* terminal, and the resulting composite signal (data + interference) is received via a *different* terminal. This separation complicates interception and extraction of the original data signal before it reaches the device's internal filtering processes.
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December 26, 2017
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